[bilky asko]

I’m going to ask what is probably a really stupid question so apologies now.

With this virtual set i knee that it was all green screen apart from the desk (minus reflection) and the wood floor under it, but in this photo it shows the screen to the right of the desk.  Is that  actually there behind the green or has someone superimposed it on to show where it is?

It's projected faintly onto the green screen so presenters have something to look at. A similar technique has been used in Jeremy Vine's green screen setups for elections, I believe.